Liquid crystal display device

ABSTRACT

A low cost LCD device employing a high speed field sequential drive scheme. The liquid crystal display device comprises: a liquid crystal display array divided into a first area, a second area and a third area, in each of which are included a plurality of pel lines; a first device for performing an operation for sequentially writing first color data, selected from data provided for red, green and blue, along the plurality of pel lines in the first area, an operation for sequentially writing second color data, selected from data provided for red, green and blue, along the plurality of pel lines in the second area, and an operation for sequentially writing third color data, selected from data provided for red, green and blue, along the plurality of pel lines in the third area; a backlight device, which is divided into N backlight sections, with N being a multiple of three (3) and is equal to or greater than (6), and which selectively generates red light, green light or blue light, wherewith N/3 backlight sections illuminate the first area, N/3 backlight sections illuminate the second area and N/3 backlight sections illuminate the third area; and a second device for sequentially activating the N/3 backlight sections for the second area to generate second color light and sequentially displaying the second color data in the second area, and for sequentially activating the N/3 backlight sections for the third area to generate third color light and sequentially displaying the third color data in the third area.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a liquid crystal display device that isdriven in accordance with a field sequential drive scheme, and morespecifically to a liquid crystal display device for which the high speedsequential drive scheme can be employed.

2. Prior Art

A field sequential drive scheme has been employed to display a colorimage on a liquid crystal display (LCD) device without using a colorfilter. According to the field sequential drive scheme, image data forone color are written to an LCD panel, and when a response time requiredfor switching the state of liquid crystal molecules has elapsed, abacklight for that color is turned in to display the image data. Thisrepetitious operation is performed for red (R), green (G) and blue (B)colors. In order to provide a satisfactorily extended turn-On period fora backlight, a high speed writing circuit (high speed driver) and a highspeed liquid crystal material are required. When the LCD panel is drivenat a frame frequency F_(f) (Hz), the time available for displaying animage in one color is ⅓ F_(f), and during this time, the writing of theimage data to the LCD panel, the switching of the state of the liquidcrystal material and the display of an image using the backlight must becompleted. When, for example, the response time of the liquid crystalmaterial is 3 ms, F_(f)=60 Hz and the duty ratio of the backlight is10%, the period T_(write)(s) for writing data to the LCD panel isrepresented by the following equation:

T_(write)={fraction (1/180)}−{fraction (3/1000)}−0.1×{fraction (1/60)}(s)≠889  (μs).

When an LCD panel using an XGA scheme (1024 picture elements (pels)(horizontally) ×768 pels (vertically) is employed, the time for writingone horizontal pel line is approximately 1 μs.

Such a high speed writing operation for one pel line can not be achievedby a currently available thin film transistor (TFT) that is made of anamorphous semiconductor and that has an operational speed ofapproximately 20 μs. To provide such a high speed writing operationrequires the employment of a TFT made of polysilicon, a high speedliquid crystal material, and a high speed driver having an operationalspeed that is higher then that of currently available drivers. However,a TFT made of polysilicon, a high speed liquid crystal material, and ahigh speed driver would be very expensive.

It is, therefore, one subject of the present invention to provide a lowcost LCD device for which a high speed field sequential drive scheme canbe employed that uses a currently available low cost write driver, and alow cost liquid crystal material.

SUMMARY OF THE INVENTION

The present invention is thus directed to a liquid crystal displaydevice comprising: a liquid crystal display array divided into a firstarea, a second area and a third area, in each of which are included aplurality of pel lines; a first means for performing an operation forsequentially writing first color data, selected from data provided forred, green and blue, along the plurality of pel lines in the first area,an operation for sequentially writing second color data, selected fromthe data provided for red, green and blue, along the plurality of pellines in the second area, and an operation for sequentially writingthird color data, selected from the data provided for red, green andblue, along the plurality of pel lines in the third area; a backlightmeans, which is divided into N backlight sections (N is a multiple of 3and is equal to or greater than 6) and which selectively generates redlight, green light or blue light, wherewith N/3 backlight sectionsilluminate the first area, N/3 backlight sections illuminate the secondarea and N/3 backlight sections illuminate the third area; and a secondmeans for sequentially activating the N/3 backlight sections for thefirst area to generate first color light and sequentially displaying thefirst color data in the first area, for sequentially activating the N/3backlight sections for the second area to generate second color lightand sequentially displaying the second color data in the second area,and for sequentially activating the N/3 backlight sections for the thirdarea to generate third color light and sequentially displaying the thirdcolor data in the third area.

The first means performs simultaneously the operation for writing thefirst color data, the operation for writing second color data and theoperation for writing the third color data.

The first area, the second area and the third area are each divided intoN/3 sub-areas, and in each of the sub-areas are included a plurality ofpel lines.

When one color data set is written in one of the sub-areas, the secondmeans activates a backlight section assigned for the sub-area, andbefore another color data set is written in the sub-area, the secondmeans deactivates the backlight section.

The same number of pel lines are included in the first area, the secondarea and the third area.

When one part of one color data set is displayed in one of thesub-areas, the following part of the color data is written in thesucceeding sub-area.

When one part of one color data set is displayed in one of thesub-areas, the following part of the color data is written across thepel lines in the succeeding multiple sub-areas.

A backlight section assigned for one of the sub-areas is turned onfollowing the expiration of a response time for a liquid crystalmaterial in the last pel line in the sub-area.

The first means writes the first color data, the second color data andthe third color data at predetermined intervals in one of the sub-areas,and a backlight section assigned for the sub-area generates light forthe first color when the first color data have been written, generateslight for the second color when the second color data have been written,and generates light for the third color when the third color have beenwritten.

The second means controls the N backlight sections so as to sequentiallydisplay the color data written in the sub-areas during a period 1/F_(f)(F_(f) is a frame frequency).

According to another aspect of the present invention, a liquid crystaldisplay device comprises: a liquid crystal display array, which includeshorizontally arranged X pels and vertically arranged Y pels, which isdivided into a first area, a second area and a third area, in each ofwhich are included horizontally extended Y pel lines, and which isdivided into N/3 sub-areas (N is a multiple of 3 and is equal to orgreater than 6); a first means for performing an operation forsequentially writing first color data, selected from data provided forred, green and blue, across Y pel lines beginning with the first pelline in the first area, continuing through the pel lines in the secondarea and ending with the last pel line in the third area, for performingan operation for sequentially writing second color data, selected fromthe data provided for red, green and blue, across Y pel lines beginningwith the first pel line in the second area, continuing through the pellines in the third area and ending with the last pel line in the firstarea, and for performing an operation for sequentially writing thirdcolor data selected form the red, green ad blue data into Y pel linesbeginning with the first pel line in the third area, continuing throughthe pel lines in the first area and ending with the last pel line in thesecond area; a backlight means, which is divided into N backlightsections and which selectively generates red light, green light or bluelight, wherewith N/3 backlight sections illuminate the first area, N/3backlight sections illuminate the second area and N/3 backlight sectionsilluminate the third area; and a second means for controlling the Nbacklight sections, so that when one color data set, selected from thedata provided for red, green and blue, have been written to one of thesub-areas, a backlight section assigned for the sub-area is turned on togenerate a light having the same color as the color data set.

According to an additional aspect of the present invention, a liquidcrystal display device comprises: a liquid crystal display array inwhich are included a plurality of pel lines; a first means forsequentially writing across the plurality of pel lines first color dataselected form data provided for red, green and blue, for sequentiallywriting across the plurality of pel lines second color data selectedfrom the data provided for red, green and blue, and for sequentiallywriting to the plurality of pel lines third color data selected from thedata provided for red, green and blue; a backlight means, which isdivided into N backlight sections (N is an integer equal to or greaterthan 2) and which selectively generates red light, green light or bluelight, whereof each of the N backlight sections is assigned for a 1/Narea in the liquid crystal display array; and a second means forsequentially activating the N backlight sections in order tosequentially display the color data written across the plurality of pellines in the liquid crystal display array.

When one color data set has been written across pel lines in the 1/Narea, the second means activates a backlight section assigned for the1/N area to generate a light having the same color as the color dataset, and then, before another color data set is written to the 1/N area,the second means deactivates the backlight section.

According to a further aspect of the present invention, a liquid crystaldisplay device comprises: a liquid crystal display array, each of whichincludes a plurality of pel lines that are sorted into a plurality ofpel line groups, each of which includes at least two continuous pellines; a first means for sequentially writing to the plurality of pelline groups first color data selected from data provided for red, greenand blue, for sequentially writing to the plurality of pel line groupssecond color data selected from the data provided for red, green andblue, and for sequentially writing to the plurality of pel line groupsthird color data selected from the data provided for red, green andblue; a backlight means, which is divided into N backlight sections (Nis an integer equal to or greater than 2) and which selectivelygenerates red light, green light or blue light, whereof each of the Nbacklight sections is assigned for a 1/N are in the liquid crystaldisplay array; and a second means for sequentially activating the Nbacklight sections in order to sequentially display the color datawritten across the plurality of pel line groups in the liquid crystaldisplay array.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings inwhich:

FIG. 1 is a block diagram illustrating a liquid crystal display (LCD)device 1 and a personal computer (PC) 2, which are employed for thescreen division scheme according to a first embodiment of the presentinvention.

FIG. 2 is a diagram showing one part of a TFT LCD array wherein aplurality of gate lines are arranged horizontally and a plurality ofdata lines are arranged vertically.

FIG. 3 is a diagram for explaining the number of backlight sections.

FIG. 4 is a diagram showing the relationship of backlight sectionsrelative to three areas, 3A, 3B and 3C, of the TFT LCD array 3.

FIG. 5 is a diagram showing a screen division scheme gate driver thatdrives Y gate lines included in the TFT LCD array of X pels×Y pels.

FIG. 6 is a diagram showing the processing for writing R, G and B imagedata in the areas 3A, 3B and 3C of the TFT LCD array.

FIG. 7 is a diagram showing the processing for writing R, G and B imagedata in the areas 3A, 3B and 3C of the TFT LCD array.

FIG. 8 is a diagram showing the processing for writing R, G and B imagedata in the areas 3A, 3B and 3C of the TFT LCD array, and the controlprovided for the backlight sections.

FIG. 9 is a diagram showing the processing for writing R, G and B imagedata in the areas 3A, 3B and 3C of the TFT LCD array, and the controlprovided for the backlight sections.

FIG. 10 is a diagram showing the processing for writing R, G and B imagedata in the areas 3A, 3B and 3C of the TFT LCD array, and the controlprovided for the backlight sections.

FIG. 11 is a diagram showing the status of images displayed on the TFTLCD array 3 at time T6.

FIG. 12 is a diagram showing the status of images displayed on the TFTLCD array 3 at time T15.

FIG. 13 is a block diagram illustrating a liquid crystal display (LCD)device and a personal computer (PC), which are employed for the timedivision scheme according to a second embodiment of the presentinvention.

FIG. 14 is a diagram showing the connection of lines originating at thedata driver to data lines in the time division scheme.

FIG. 15 is a diagram showing the relationship of backlight sectionsrelative to the TFT LCD array in the time division scheme.

FIG. 16 is a diagram showing a time division scheme gate driver 5 thatdrives Y gate lines in the TFT LCD array of X pels×Y pels.

FIG. 17 is a diagram showing the processing in the time division schemefor writing R, G and B image data in the display areas of the TFT LCDarray.

FIG. 18 is a diagram showing the processing in the time division schemefor writing R, G and B image data in the display areas of the TFT LCDarray.

FIG. 19 is a diagram showing the processing for writing R, G and B imagedata in the display areas of the TFT LDC array, and the control providedfor the backlight sections.

FIG. 20 is a diagram showing the processing for writing R, G and B imagedata in the display areas of the TFT LCD array, and the control providedfor the backlight sections.

FIG. 21 is a diagram showing the processing for writing R, G and B imagedata in the display areas of the TFT LCD array, and the control providedfor the backlight sections.

FIG. 22 is a diagram showing the status of images displayed on the TFTLCD array at time T6.

FIG. 23 is a diagram showing the status of images displayed on the TFTLCD array at time T15.

FIG. 24 is a diagram showing another example of the backlight.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 is a block diagram illustrating a liquid crystal display device(LCD) 1 and a personal computer (PC) 2, which are employed for thescreen division method according to a first embodiment of the presentinvention. The LCD device 1 comprises: a thin film transistor (TFT) LCDarray 3; a backlight 4; a gate driver 5; a data driver, i.e., a sourcedriver 6; and LCD controller 7; and a backlight driver 8. According tothe screen division method, the display screen of the TFT LCD array 3 isdivided into three areas 3A, 3B and 3C.

In FIG. 2 is shown one part of the TFT LCD array 3. A plurality of gatelines are horizontally provided in the TFT LCD array 3, and a pluralityof data lines are vertically provided in the TFT LCD array 3. One TFTthat constitutes one picture element, i.e., one pixel (pel), isconnected at each of the intersections of the gate lines and the datalines. A plurality of pels that are connected to a single gate line arecollectively called a pel line. More specifically, a gate electrode inthe TFT is connected to the gate line, a source electrode is connectedto one of the four data lines, i.e., one of the four source lines, and adrain electrode is connected to a display electrode that is composed ofindium tin oxide (ITO). When a gate pulse is applied to the gate linesby the gate driver 5 and a voltage signal representing data is appliedto one of the data lines by the data driver 6, the TFT is turned on, thevoltage signal is transmitted to a capacitor (not shown), and a chargeaccumulated in the capacitor is applied to the display electrode, sothat the state of the liquid crystal molecules is changed from a statewherein light from the backlight is passed. The time required forswitching from one state to another is called a response time T_(res)for a liquid crystal material. The reason that four data lines areprovided will be explained later.

The backlight 4 will now be described. The backlight 4 of the presentinvention is vertically divided into a plurality of backlight sections#0, #1, #2, . . . in the TFT LCD array 3. One backlight section isassigned for a predetermined number of pel lines. The ON/OFF states ofthe individual backlight sections are independently controlled by thebacklight driver 8. Basically, the backlight sections are sequentiallyturned on or off from the top to the bottom of the TFT LCD array 3. TheLCD controller 7 supplies image data, i.e., R, G and B data, throughthree data ports to the data driver 6 for controlling the operation ofthe data driver 6, and controls the gate driver 5 and the backlightdriver 8 by using control lines 14 and 15. More specifically, the LCDcontroller 7 transmits a shift clock across the control lines 14 and 15to the gate drive 5 and to the backlight driver 8. A signal “duty,”which represents the number of backlights that are turned on at the sametime, and a signal “shift,” which represents the shifting distance forthe backlight section, are transmitted to the backlight driver 8. In thefirst embodiment, concerning the screen division method, and the secondembodiment, concerning a time division method, the value of the “duty”signal is “1,” and the value of the “shift” signal is “1”. Therefore, inthe screen division method, one of N/3 backlight sections is temporarilyturned on, following which the adjacent backlight section is turned on.

The PC 2 comprises: a video random access memory (VRAM) R 9 in which red(R) image data are stored; a VRAM G 10 in which green (G) image data arestored; a VRAM B 11 in which blue (B) image data are stored; and a videocontroller 12. The video controller 12 accesses the VRAM 9, 10 and 11 totransmit the R, G, B data the LCD controller 7.

The number of backlight sections will now be explained while referringto FIG. 3. First, assume that the backlight 4 is divided into Nbacklight sections, and that the number 4 is divided into N backlightsections, and that the number of pel lines in the 1/N area is J+1. Theimage data are sequentially written to the TFT LCD array 3 beginning atthe first line 0. The backlight sections assigned for the pel lines 0 toJ can be turned on after the response time T_(res) for the liquidcrystal material of line J has elapsed. That is, when image data arewritten to lien I, the backlight sections assigned for the pel lines 0to J are turned on. The backlight sections can be sequentially turned onuntil image data have been written across the last line. The ON periodfor the backlight section that illuminates the line J is calledT_(flash). Assuming that the frame frequency is F_(f) (Hz), one frameperiod for displaying one of R, G and B images is 1/F_(f), and asub-frame period is ⅓ F_(f). The duty ratio that represents theillumination ratio is obtained from the following equation:

 Duty ratio=T_(flash)×F_(f),

wherein t_(flash)=1/(3×F_(f))−1/(3×F_(f))×1/N−T_(res)(sec). Thus, theduty (T_(p))=⅓×(1−1/N)−F_(f)×T_(res). From the above equation, N isrepresented as N=1/[1−3×(T_(D)+F_(f)×T_(res))].

When the parameters, i.e., the duty ratio, F_(f) and T_(res), aresubstituted into the above equation, N, i.e., the number of backlightsections, can be obtained. The following Table 1 shows the number ofbacklight sections when the duty ratio=0.1 (10%) and T_(res)=(ms).

TABLE 1 F_(f) (HZ) 22 Hz 40 Hz 50 Hz 60 Hz 70 Hz screen division methodN = 6 N = 9  N = 12 N = 21 N = 45 time division method N = 2 N = 3 N = 4N = 7  N = 15

In the screen division method, N is a multiple of 3. It should be notedthat N is equal to or greater than 6 and is smaller than the total countof the pel lines in the TFT LCD array 3. The time division methodemployed for the second embodiment will be described later.

In FIG. 4 is shown the relationship between the backlight sections andthe three areas 3A, 3B and 3C in the TFT LCD array 3. To simplify thescreen illustration and the explanation, N=9 is employed in Table 1. Thebacklight sections #0, #1 and #2 are assigned for the first ⅓, area 3A,of the TFT LCD array 3; the backlight sections #3, #4 and #5 areassigned for the second ⅓, area 3B, of the TFT LCD array 3; and thebacklight sections #6, #7 and #8 are assigned for the third ⅓, area 3C,of the TFT LCD array 3. The individual backlight sections each include ared (R) light-emitting diode (LED), a green (G) light-emitting diode(LED) and a blue (B) light-emitting diode (LED). The backlight driver 8selectively activates one of the R, G and B LEDs. A cross section of thebacklight is shown in the lower portion in FIG. 4. Light emitted fromone of the R, G and B LEDs enters an optical guide 18, and the lightreflected therefrom is forwarded to the TFT LCD array 3 through a lightscattering sheet 19.

In FIG. 5 is shown the gate driver 5 that drives Y gate lines in the TFTLCD array 3 that is composed of X pels×Y pels. The present invention canbe applied for TFT LCD arrays that have the various resolutions shown inTable 2.

TABLE 2 Scheme XGA SXGA USGA QXGA Resolution 1024 × 768 1280 × 1024 1600× 1200 2048 × 1536 (X × Y)

As was previously explained, the TFT LCD array 3 is divided into threeareas, i.e., the first area 3A, the second area 3B and the third area3C. The first, the second and the third areas 3A, 3B and 3C, eachinclude Y/3 pel lines that extend horizontally. In the screen divisionmethod, the gate driver 5 has Y/3 gate lines. The gate driver 5activates at the same time a gate line 0, which is forwarded to thefirst pel line 0 in the first area 3A, a gate line Y/3, which isforwarded to the first pel line Y/3 in the second area 3B, and a gateline 2Y/3, which is forwarded to the first pel line 2Y/3 in the thirdarea 3C, and at the same time activates a gate line 1, which isforwarded to the second pel line 1 in the first area 3A, a gate lineY/3+1 in the second area 3B, and a gate line 2Y/3+1, which is forwardedto the second pel line 2Y/3+1 in the third area 3C.

In FIGS. 6 and 7 are shown the writing operation where R, G and B imagedata in the VRAM R 9, the VRAM G 10 and the VRAM B 11 are writtenthrough the video controller 12 and the LCD controller 7 to the areas3A, 3B and 3C in the TFT LCD array 3 during a time period represented by1/F_(f) (F_(f) is a frame frequency), i.e., during a period extendingfrom the T1 to time T27. In FIG. 6, Xs represent the number of pelshorizontally arranged in the TFT LCD array 3. It should be noted thatthe TFT LCD array 3 of X×Y pels is an elongated box that is extendedvertically. To simplify the explanation, as was previously mentioned,the number of pels vertically arranged in the TFT LCD array 3 is Y=27.

Therefore, the first area 3A includes Y/3 pel lines, i.e., nine pellines I0 to I8; the second area 3B includes Y/3 pel lines, i.e., ninepel lines J0 to J8; and the third area 3C includes Y/3 pel lines, i.e.,nine pel lines K0 to K8. The pel line I0 corresponds to pel line 0 inFIG. 5, and the pel line I8 corresponds to pel line Y/3−1. The pel lineJ0 corresponds to pel line Y/3, and the pel line J8 corresponds to pelline 2Y/3−1. The pel line K0 corresponds to pel line Y−1.

The VRAM R 9 is used to store R data for X×Y pels, the VRAM G 10 is usedto store G data for X×pels, and the VRAM B 11 is used to store B datafor X×Y pels. The data to be stored in the VRAMs 9, 10 and 11 representthe data to be written to X pels across one pel line. If the SGA schemein Table 2 is employed, the data in the individual locations in theVRAMs represent data for 1024 pels across one pel line in the TFT LCDarray 3. For example, data R0 represents R data written 1024 pels acrossthe pel line I0. Multilevel R data R0 to R26 are stored in the VRAM R 9,multilevel G data G0 to G26 are store in the VRAM G 10, and multilevel Bdata B0 to B26 are stored in the VRAM B 11. One R data set, one G dataset, and one B data set are written at the same time to the three areas,3A, 3B and 3C, in the TFT LCD array 3 during one write cycle TN (n=1, 2,3, . . . ). The time extending from T1 to T27 represents a frame period1/F_(f). The number of times T in the frame period equals the number ofpel lines in the TFT LCD array 3. Pointers P_(R), P_(G) and P_(B), forthe VRAMs 9, 10 and 11 shown,in FIGS. 1 and 6, indicate the positionswhereat the reading of data from the VRAMS is initiated. In this case.,during the write cycle T1, the pointer P_(R) points to data R0 in theVRAM R 9, the pointer P_(G) points to data R0 in the VRAM R 9, thepointer P_(G) points to data G9 in the VRAM G 10, and the pointer P_(B)points to data B18 in the VRAM B 11. As is shown in FIGS. 6 and 7,during the period extending from T1 to time T27, R data R0 through R26are sequentially written across the pel lines I0 to K8, G data G9through G8 are sequentially written across the pel lines J0 to I8, and Bdata B18 through B17 are sequentially written to the pel lines K0 to J8.More specifically, at time T1, data R0, G9 and B18 are respectivelywritten across pel lines I0, J0 and K0, at time T2, data R1, G10 and B19are respectively written across pel lines I1, J1 and K1, and at time T3,data R2, G11 and B20 are respectively written across pel lines I2, J2and K2. This process is repeated hereinafter.

The writing operation will be explained while referring to FIGS. 2, 5and 6. At this T1, the gate driver 5 supplies a gate pulse to the gatelines 0, Y/3 and 2Y/3. The data driver 6 supplies data R0 to data linesDL0 (0) through DLX-1 (0), data G9 to data lines DL0 (1) through DLX-1(1), and data B18 to data lines DL0 (3) through DLX-1 (3).

At time T2, the gate driver 5 supplies a gate pulse to the gate lines 1,Y/3+1 and 2Y/3+1. The data driver 6 supplies data R1 to data lines DL0(1) through DLX-1 (1), data G10 to data lines DL0 (2) through DLX-1 (2),and data B19 to data lines DL0 (0) through DLX-1 (0).

At time T3, the gate driver 5 supplies a gate pulse to the gate lines 2,Y/3+2 and 2Y/3+2. The data driver 6 supplies data R2 to data lines DL0(2) through DLX-1(2), data G11 to data lines DL0 (3) through DLX-1 (3),and data B20 to data lines DL0 (1) through DLX-1 (1). This operations isrepeated during a plurality of frame cycles.

As is described above, the video controller 12 and the LCD controller 7sequentially write the first color data, which are selected from R, Gand B data, across Y pel lines beginning with the first pel line in thefirst area 3A continuing through the second area 3B and ending with thelast pel line in the third area 3C; sequentially write the second colordata, which are selected from R, G and B data, to Y pel lines beginningwith the first pel line in the second area 3B, continuing through thethird area 3C and ending with the last pel line in the first area 3A;and sequentially write the third color data, which are selected from R,G and B data, to Y pel lines beginning with the first pel line in thethird area 3C, continuing through the first area 3A and ending with thelast pel line in the second area 3B.

In FIGS. 8, 9 and 10 is shown the writing operation whereby R, G and Bimage data in the VRAM R 9, VRAM G 10 and VRAM B 11 are written to theareas 3A, 3B and 3C of the TFT LCD array 3 during a period extendingfrom time T1 to time T35, and is also shown the control for thebacklight sections #0 to #8. As was previously described, N=9 isemployed as the number of backlights, and the first, the second and thethird areas, 3A, 3B and 3C, are assigned for one sub-area. The backlightsection #0, for example, is assigned for the sub-area that includes pellines I0, I1 and I2. N/3 backlight sections #0 to #2 illuminate thefirst area 3A N/3 backlight sections #3 to #5 illuminate the second area3B, and N/3 backlight sections #6 to #8 illuminate the third and 3C. TheLCD controller 7 and the backlight driver 8 control the backlightsections #0 to #8, so that when either R, G or B data are written to oneof the sub-areas, the backlight section assigned for the sub-area isturned on to generate a light having the same color as the color data.That is, the backlight section is turned on following the elapse of theresponse time for the liquid crystal material in the last pel line inthe corresponding sub-area.

A period extending from time T1 to T27 represents the first frame period1/F_(f) (s), and the second frame period starts at time T28 (F_(f) is aframe frequency). The times T1 to T35 are shown in FIGS. 8 to 10 inorder to explain the operation performed with the screen divisionmethod. In the initial state, all the backlight sections, #0 to #8, areturned off, and all the pixels or pels in the TFT LCD array 3 are reset,i.e., cleared.

One of the R, G and B LEDs for one backlight section is turned onfollowing the elapse of the response time T•_(res) for the liquidcrystal material in the last pel line that the backlight sectionilluminates. In this example, the response time T_(res) is equal to thesum of two periods, i.e., the sum of two write cycles. The ON operationfor each backlight section is continued for a predetermined period,e.g., a time equivalent to the time allocated fro three write cycles.The R LED in the backlight section #0, for example, is turned on at timeT6 following the elapse of the response time T_(res) for the liquidcrystal material in the pel line I2, e.g., following the elapse of thetimes T4 and T5. The ON state of the backlight section #0 is continuedfrom time T6 to time T8. then during the response time T_(res) for theliquid crystal material, and the ON period for the backlight section,the next data, e.g., R data R3 to R7, are written to the succeedingmultiple pel lines.

The operation during a period extending from time T1 to time T8 is asfollows:

Operation for R data:

During a period extending from time T1 to T3, data R0 to R2 are writtenacross pel lines I0 to I2 in a sub-area for which the backlight section#0 is turned on at time T6, following the elapse of the response timeT_(res) for the liquid crystal material in the last pel line I2 that isilluminated by the backlight section #0. The ON state of the R LED forthe backlight section #0 is continued from time T6 to time T8, and Rdata R0 to R2 are displayed. During the response time T_(res), i.e., aperiod extending from time T4 to T5, and during the ON period for thebacklight section #0, i.e., a period extending from time T6 to time T8,the succeeding data R3 to R7 are written across the succeeding pel linesI3 to I7. It should be noted that the R LED for the backlight section #0is turned off before the next data B0 are written across the pel line I0at time T10. Time T9 is used as a margin between the ON period for thebacklight section #0 and the period for writing the next data B0.

Operation for G data:

During a period extending from time T1 to T3, data G9 to G11 are writtenacross pel lines J0 to J2 in a sub-area for which the backlight section#3 is assigned. The G LED for the backlight section #3 is turned on attime T6, following the response time T_(res) of the liquid crystalmaterial in the last pel line J2 that is illuminated by the backlightsection #3. The ON state for the G LED of the backlight section #3 iscontinued from time T6 to time T8, and G data G9 to G11 are displayed.During the response time T_(res), i.e., a period extending from time T4to T5, and during the ON period for the backlight section #3, i.e., aperiod extending from time T6 to time T8, the succeeding data G12 to G16are written across the succeeding pel lines J3 to J7. It should be notedthat the G LED for the backlight section #3 is turned off before thenext data R9 are written to the pel line J0 at time T10. Time T9 is usedas a margin between the ON period for the backlight section #3 and theperiod for writing the next data R9.

Operation for B data: During a period extending from time T1 to T3, dataB18 to B20 are written across pel lines K0 to K2 in a sub-area for whichthe backlight section #6 is assigned. The B LED of the backlight section#6 is turned on at time T6, following the elapse of the response timeT_(res) for the liquid crystal material in the last pel line K2 that isilluminated by the backlight sections #6. The ON state of the B LED forthe backlight section #6 is continued from time T6 to time T8, and Bdata B18 to B20 are displayed. During the response time T_(res), i.e., aperiod extending from time T4 and T5, and during the ON period for thebacklight section #6, i.e., a period extending from time T6 to time T8,the succeeding data B21 to B25 are written across the succeeding pellines K3 to K7. It should be noted that the B LED for the backlightsection #6 is turned off before the next data G18 are written across thepel line K0 at time T10. Time T9 is used as a margin between the ONperiod of the backlight section #6 and the period for writing the nextdata G18.

The operation during a period extending from time T9 to time T11 is asfollows:

Operation for R data:

The LED for the backlight section #1 is turned on at time T9, followingthe elapse of the response time T_(res) for the liquid crystal materialin the last pel line I5 that is illuminated by the backlight section #1is continued from time T9 to time T11, and R data R3 to R5 aredisplayed. During the ON period for the backlight section #1, thesucceeding data R8 to R10 are written across the succeeding pel lines I8to J1. It should be noted that the R LED for the backlight section #1 isturned off before the next data B3 are written across the pel line I3 attime T13. Time T12 is used as a margin between the ON period for thebacklight section #1 and the period for writing the next data B3.

Operation for G data:

The G LED for the backlight section #4 is turned on at time T9,following the elapse of the response time T_(res) for the liquid crystalmaterial in the 1st pel line J5 that is illuminated by the backlightsection #4. The ON state of the G LED for the backlight section #4 iscontinued from time T9 to time T11, and G data G12 to G14 are displayed.During the ON period for the backlight section #4, the succeeding G dataG17 to G19 are written across the succeeding pel lines J8 to K1. Itshould be noted that the G LED for the backlight section #4 is turnedoff before the next data R12 are written across the pel line J3 at timeT13. Time T12 is used as a margin between the ON period for thebacklight section #4 and the period for writing the next data R12.

Operation for B data:

The B LED for the backlight section #7 is turned on at time T9,following the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line K% that is illuminated by the backlightsection #7. The ON state of the B LED for the backlight section #7 iscontinued from T9 to time T11, and B data B21 to B23 are displayed.During the ON period for the backlight section #7, the succeeding B dataB26, B0 and B1 are written across the succeeding pel lines K8, I0 to I1.It should be noted that the B LED for the backlight section #7 is turnedoff before the next data G21 are written across the pel line K3 at timeT13. Time T12 is used as a margin between the ON period for thebacklight section #7 and the period for writing the next data G21.

The operation during a period extending from time T12 to time T14 is asfollows:

Operation for R data:

The R LED for the backlight section #2 is turned on at time T12,following the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line I8 that is illuminated by the backlightsection #2. The ON state of the R LED for the backlight section #2 iscontinued from time T12 to time T14, and R data R6 to r8 are displayed.During the ON period for the backlight section #2, the succeeding dataR11 to R13 are written across the succeeding pel lines J2 to J4. Itshould be noted that the R LED for the backlight section #2 is turnedoff before the next data B6 are written across the pel line I6 at timeT16. Time T15 is used as a margin between the ON period for thebacklight section #2 and the period for writing the next data B6.

Operation for G data: The G LED for the backlight section #5 is turnedon at time T12, following the elapse of the response time T_(res) forthe liquid crystal material in the last pel line J8 that is illuminatedby the backlight section #5. The ON state of the G LED for the backlightsection #5 is continued from time T12 to time T14, and G data G15 to G17are displayed. During the ON period for the backlight section #5, thesucceeding G data G20 to G22 are written across the succeeding pel linesK2 to K4. It should be noted that the G LED for the backlight section #5is turned off before the next data R 15 are written across the pel lineJ6 at time T16. Time T15 is used as a margin between the ON period forthe backlight section #5 and the period for writing the next data R15.

Operation for B data:

The B LED for the backlight section #8 is turned on at time T12,following the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line K8 that is illuminated by the backlightsection #8. The ON state of the B LED for the backlight section #8 iscontinued from time T12 to time T14, and B data B24 to B26 aredisplayed. During the ON period for the backlight section #8, thesucceeding B data B2 to B4 are written across the succeeding pel lies I2to I4. It should be noted that the B lED for the backlight section #8 isturned off before the next data G24 are written across the pel line K6at time T16. Time T15 is used as a margin between the ON period for thebacklight section #8 and the period for writing the next data G24. Theoperation during a period extending from time T15 to time T17 is asfollows:

Operation for R data:

The R LED for the backlight section #3 is turned on at time T15,following the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line J2 that is illuminated by the backlightsection #3. The ON state of the R LED for the backlight section #3 iscontinued from time T15 to time T17, and R data R9 to R11 are displayed.During the ON period for the backlight section #3, the succeeding dataR14 to R16 are written across the succeeding pel lines J5 to J7 Itshould be noted that the R LED for the backlight section #3 is turnedoff before the next data B9 are written across the pel line J0 at timeT19. Time T18 is used as a margin between the ON period for thebacklight section #3 and the period for writing the next data B9.

Operation for G data:

The G LED for the backlight section #6 is turned on at time T15,following the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line K2 that is illuminated by the backlightsection #6. The ON state of the G LED for the backlight section #6 iscontinued from time T15 to time T17, and G data G18 to G20 aredisplayed. During the ON period for the backliqht section #6, thesucceeding G data G23 to G25 are written across the succeeding pel linesK5 to K7. It should be noted that the G LE for the backlight section #6is turned off before the next data R18 are written across the pel lineK0 at time T19. Time T18 is used as a margin between the ON period forthe backlight section #6 and the period for writing the next data R18.

Operation for B data:

The B LED for the backlight section #0 is turned on at time T15,following the elapse of the response time T_(res) for liquid crystalmaterial in the last pel line I2 that is illuminated by the backlightsection #0. The ON state of the B LED for the backlight section #0continued from time T15 to time T17, and B data B0 to B2 are displayed.During the ON period for the backlight section #0, the succeeding B dataB5 to B7 are written across the succeeding pel lines I5 to I7. It shouldbe noted that the B LED for the backlight section #0 is turned offbefore the next data GO are written across the pel line I0 at time T19.Time T18 is used as a margin between the ON period for the backlightsection #0 and the period for writing the next data G0.

The above described operation for displaying R, G and B data is repeatedas shown in FIGS. 9 and 10. During the display operation, the R LEDs forthe backlight sections #0 to #8 are sequentially turned on to display Rdata. As is shown is FIG. 10, during the second frame period extendingfrom time T28 to T35, data R0 to R7 are again written across the pellines I0 to I7. The R LEDs for the backlight section #0 to #8 are turnedon following the elapse of the response time T_(res) for the liquidcrystal material in the last pel lines that are illuminated by thebacklight sections #0 to #8. The R LEDs for the backlight sections #0 to#8 remain on for a predetermined period in order to display R data. TheG LEDs of the backlight sections #3 to #2 are sequentially turned on todisplay G data. As is shown in FIG. 10, in the second frame periodextending from time T28 to T35, data G9 to G16 are again written acrossthe pel lines J0 to J7. The G LEDs for the backlight sections #3 to #2are turned on following the elapse of the response time T_(res) for theliquid crystal material in the last pel lines that are illuminated bythe backlight sections #3 and #2. The G LEDs for the backlight sections#3 to #2 remain on for a predetermined period in order to display Gdata. The B LEDs for the backlight sections #6 to #5 are sequentiallyturned on to display B data. As is shown in FIG. 10, in the second frameperiod extending from time T28 to T35, data B18 to B25 are again writtenacross the pel lines K0 to K7. The B LEDs for the backlight sections #6to #5 are turned on following the elapse of the response time T_(res)for the liquid crystal material in the last pel lines that areilluminated by the backlight sections #6 to #5. The B LEDs for thebacklight sections #6 to #5 remain on for a predetermined period inorder to display B data.

As is apparent from the above description, the first area 3A, the secondarea 3B and the third area 3C are each divided into N/3 sub-areas, eachof which includes a plurality of pel lines. While one part of the colordata, e.g., color data R0 to R2 written in a specific sub-area thatincludes line I0 to I2, is displayed by R light that is emitted by the RLED for he backlight section #0 that is assigned for the specificsub-area, another part of the color data, e.g., data R5 to R7, iswritten to pel lines I5 to I7 in the succeeding two sub-areas.

The first color data, e.g., R data R0 to R2, the second color data,e.g., B data B0 to B2, and the third color data, e.g., G data G0 to G2,are written sequentially at predetermined intervals in a specificsub-area, e.g., a sub-area including pel lines I0 to I2. Then, thebacklight section assigned for the sub-area, e.g., a backlight section#0, generates a light for the first color after the first color data, Rdata, have been written to the sub-area, generates a light for thesecond color after the second color data, B data, have been written tothe sub-area, and generates a light for the third color after the thirdcolor data, G data, have been written in the sub-area.

Table 3 shows the timings for the display of R, G and B color images onthe pel lines during the first frame period, extending from time T1 toT27, and during the second frame period, extending from time T28 to T35.

TABLE 3 B/L section Pel line R color G color B color #0 I0-I2 T6-T8T24-T26 T15-T17 #1 I3-T5  T9-T11 T27-T29 T18-T20 #2 I6-I8 T12-T14   T30-T-32  T21-T23 #3 J0-J2 T15-T17 T6-T8 T24-T26 #4 J3-J5 T18-T20 T9-T11  T-27-T29    #5 J6-J8 T21-T23 T12-T14 T30-T32 #6 K0-K2 T24-T26T15-T17 T33-T35 #7 K3-K5 T27-T29 T18-T20  T9-T11 #8 K6-K8 T30-T32T21-T23  T-12-T-14   

The above operation is repeated to display color images on the TFT LCDarray 3.

As was previously described, according to the screen division method, Nis a multiple of 3 that is equal to or greater than 6 and is smallerthan the total count of pel lines included in the TFT LCD array 3. Thereason that N is a multiple of 3 that is equal to or greater than 6 isas follows. If “3” is employed for N, one backlight section can be usedfor the first area 3A, the second backlight section can be used for thesecond area 3B, and the third backlight section can be used for thethird area 3C. As for the operation performed for the first area 3A, asis shown in FIG. 8, R data R0 to R8 are written across pel lines I0 toI8 during a period extending from T1 to T9, and the succeeding B data B0are written across the pel line I0 at time T10. After the R data R0 toR8 have been written, the backlight section for the first area 3A mustbe turned on to display these data, and must be turned off before thesucceeding data, and must be turned off before the succeeding data B0are written. If the liquid crystal material has an extremely fastswitching speed, the backlight section may be turned on for the timeextending from time T9 to time T10. However, switching the state of theliquid crystal materials withing such a short time is impossible.Therefore, the value of N is set to a multiple of 3, and is equal to orgreater than 6.

In FIGS. 11 and 12 are shown the statuses of an image displayed on theTFT LCD array at time T6 and T15. In FIG. 11, at time T6, while data R5are being written across pel line I5, the R LED for the backlightsection #0 is turned on. Accordingly, R data on pel lines I0 to I2 aredisplayed and the R data on the pel lines I3 to I5 are not displayed.While data G14 are being written across pel line J5, the G LED for thebacklight section #3 is turned on. Accordingly, the G image data on thepel lines J3 to J5 are not displayed, and the G data on the pel lines J3to J5 are not displayed. While data B23 are being written across pelline K5, the B LED for the backlight section #6 is turned on.Accordingly, the B image data on the pel lines K0 to K2 are displayed,and the B data on the pel lines K3 to K5 are not displayed.

In FIG. 12, at time T15, while data B5 are being written across pel lineI5, the B LED for the backlight section #0 is turned on. Accordingly, Bimage data on pel lines I0 to I2 are displayed and the B data on the pellines I3 to I5 are not displayed. While data R14 are being writtenacross pel line J5, the R LED for the backlight section #3 is turned on.Accordingly, the R image data on the pel lines J0 to J2 are displayed,and the R data on the pel lines J3 to J5 are not displayed. While dataG23 are being written across pel line K5, the G LED for the backlightsection #6 is turned on. Accordingly, the G image data on the pel linesK0 to K2 are displayed, and the G data on the pel lines K3 to K5 are notdisplayed.

In FIG. 12, at time T15, while data B5 are being written across pel lineI5, the B LED for the backlight section #0 is turned on. Accordingly, Bimage data on pel lines I0 to I2 are displayed and the B data on the pellines I3 to I5 are not displayed. While data R14 are being writtenacross pel line J5, the R LED for the backlight section #3 is turned on.Accordingly, the R image data on the pel lines J0 to J2 are displayed,and the R data on the pel lines J3 to J5 are not displayed. While dataG23 are being written across pel line K5, the G LED for the backlightsection #6 is turned on. Accordingly, the G image data on the pel linesK0 to K2 are displayed, and the G data on the pel lines K3 to K5 are notdisplayed.

In the first embodiment, the TFT LCD array 3 is divided into threeareas, 3A, 3B and 3C, that are driven by a single data driver 6. In thesecond embodiment, a data driver can be provided on the upper side andlower side of the TFT LCD array 3. In this embodiment, the display areafor the TFT LCD array 3 is divided into an upper half and a lower half,and the upper half portion is further divided into three areas, 3A, 3Band 3C, each of which is driven by the data driver provided on the upperside. Similarly, the lower half portion is divided into three areas, 3A,3B and 3C, each of which is driven by the data driver provided on thelower side.

FIG. 13 is a block diagram illustrating a liquid crystal display (LCD)device and a personal computer (PC) 2 that are employed for the timedivision method according to the second embodiment of the presentinvention. Since the essential blocks in FIG. 13 are substantially thesame as those in FIG. 1, the same reference numerals are used to denotethese components, and no detailed explanation for them will be given. Asin the screen division method in the first embodiment, the TFT LCD array3 includes horizontal X pels and vertical Y pels. In this embodiment,Y=27 is also employed. The differences between the time division methodin FIG. 13 and the screen division method are: the simultaneous writingof R, G and B data, as is inherent to the screen division scheme, is notperformed; the number of backlight sections, if the same frame frequencyis employed, is smaller than that for the screen division scheme; thepointers P_(R), P_(G) and P_(B), which point to start positions for thereading of R, G and B data, point to the first addresses in the VRAM R9, the VRAM G 10 and the VRAM B 11; and the connection of the gate linesand the data lines to the TFT differ from procedure for the screendivision scheme.

In FIG. 14 is shown the connections in the time division scheme for datalines originating at the data driver 6. Three data lines DL0 (0), DL0(1) and DL0 (2), are connected to the source electrodes of the TFT 16.

In FIG. 15 is shown the relationship between the backlight sections andthe display areas in the TFT LCD array 3. In the time division scheme,the number of backlight sections, N, is equal to or greater than 1, andis smaller than the total count of the pel lines included in the TFT LCDarray 3. To simplify the drawings and the description, in Table 1 N=3 isemployed. The backlight section (B/L) #0 is assigned for the first ⅓area of the TFT LCD array 3, the backlight section (B/L) #1 is assignedfor the second ⅓ area of the TFT LCD array 3, and the backlight section(B/L) #2 is assigned for the third ⅓ area of the TFT LCD array 3. Thebacklight sections each include R (red), G (green) and B (blued) LEDs.The backlight driver 8 selectively activates the R, G and B LEDs.

In FIG. 16 is shown the gate driver 5 for driving Y gate lines in theTFT LCD array 3 consisting of X pels×Y pels. The gate driver 5 activatesa plurality of gate lines at the same time. In this embodiment, the gatedriver 5 activates three gate lines at a time, and therefore, has Y/3gate output lines, as in the screen division scheme. More specifically,the gate driver 5 simultaneously activates gate lines 0 to 2, thenactivates gate lines 3 to 5, and thereinafter activates the remaininggate lines in order.

FIGS. 17 and 18 are shown the writing operation whereby R, G and B imagedata, from the VRAM R 9, the VRAM G 10 and the VRAM B 11, aretransmitted through the video controller 12 and the LCD controller 7 andare written in the display areas in the TFT LCD array 3 during a periodrepresented by 1/F_(f) (F_(f) is a frame frequency), i.e., during aperiod extending from time T1 to time T27. As is explained whilereferring to FIGS. 6 and 7, Xs represent the number of the pelshorizontally arranged in the TFT LCD array 3. It should be noted thatthe TFT LCD array 3 of X×Y pels is an elongated box that is extendedvertically. Since Y-27 is also employed in the second embodiment, theTFT LCD array 3 has 27 pel lines, I0 to I26. In this embodiment, 27 pellines are sorted into nine pel line groups, each of which includes threepel lines. For example, the first pel line group includes pel line I0 toI2, and the last pel line group includes pel lines I24 and I26.Therefore, color data are written across three pel lines at a time. Itis preferable that for high speed processing each pel line group includeat least two pel lines, but it is also possible to write color dataacross a single pel line at a time.

As in the screen division scheme, the VRAM R9 is used to store R datafor X×Y pels, the VRAM G 10 is used to store G data for X×Y pels, andthe VRAM B 11 is used to store B data for X×Y pels. The data to bestored in the VRAMs 9, 10 and 11 represent the data that is to bewritten to X pels across one pel line. Multilevel R data R0 to R26 arestored in the RAM R 9, multilevel G data G0 to G26 are stored in theVRAM G 10, and multilevel B data B0 to B26 are stored in the VRAM B11.The time extending from T1 to T27 represents a frame period 1/F_(f). Thenumber of times T in the frame period equals the number of pel lines inthe TFT LCD array 3. Pointers P_(R), P_(G) and P_(B), for the VRAMs 9,10 and 11 shown in FIG. 13 and 17, indicate the positions whereat thereading of data from the VRAMs is initiated. In this case, during thewrite cycle T1, the pointer P_(R) points to data R0 in the VRAM R 9, thepointer P_(G) points to data G0 in the VRAM G 10, and the pointer P_(B)points to data B0 in the VRAM B11.

In this embodiment employing the time division scheme, at time T aplurality of data sets for the same color, i.e., three data sets, arewritten across one pel line group of the TFT LCD array 3. The writingoperation performed by the video controller 12 and the LCD controller 7will now be described while referring to FIGS. 14, 16 and 17. At timeT1, the gate driver 5 supplies a gate pulse to the gate lines 0, 1 and2. The data driver 6 supplies data R0 to data lines DL0 (0) throughDLX-1 (0), data R1 to data lines DL0 (1) through DLX-1 (1), and data R2to data lines DL0 (2) through DLX-1 (2). As a result, data R0 to R2 arewritten across the pel lines I0 to I2.

At time T2, the gate driver 5 supplies a gate pulse to the gate lines 3,4 and 5. The data driver 6 supplies data R3 to data lines DL0 (0)through DLX-1 (0), data R4 to data lines DL0 (1) through DLX-1 (1), anddata R5 to data lines DL0 (2) through DLX-1 (2). As a result, data Re toR5 are written across the pel lines I3 to I5. The writing operation isrepeated until at time T9 data R24 to R26 are written across pel linesI24 to I26.

When R data R0 to R26 have been written to the TFT LCD array 3 during aperiod extending from time T1 to T9, at time T10 writing of data G0 toG2 across pel lines I0 to I2 is initiated, and during a period extendingfrom time T10 to T18 G data G0 to G26 are written across pel lines I0 toI26. When G data G0 to G26 have been written to the TFT LCD array 3during a period extending from time T10 to T18, at time T19 writing ofdata B0 to B2 across pel lines I0 to I2 is initiated, and during aperiod extending from time T19 to T27 B data B0 to B26 are writtenacross pel lines I0 to I26. In this manner, R, G and B data are writtento the TFT LCD array 3 during a frame period 1/F_(f) extending from T1to T27.

In FIGS. 19, 20 and 21 are shown the writing operation whereby R, G andB image data in the VRAM R 9, VRAM G 10 and VRAM B 11 are written to thedisplay areas of the TFT LCD array 3 during a period extending from timeT1 to time T32, and are also shown the control for the backlightsections #0 to #2. In this embodiment, the backlight section #0 isassigned for the first ⅓ area that includes pel lines I0 to I8, thebacklight section #1 is assigned for the second ⅓ area that includes pellines I9 to I17, and the backlight section #2 is assigned for the third⅓ area that includes pel lines I18 to I26.

The LCD controller 7 and the backlight driver 8 control the backlightsections #0 to #2, so that when either R, G or B color data are writtento one 1/N area, the backlight section assigned for the 1/N area isturned on to generate a light having the same color as the color data.That is, the backlight section is turned on following the elapse of theresponse time for the liquid crystal material in the last pel line inthe corresponding 1/N area.

A period extending from time T1 to T27 represents the first frame period1/F_(f) (s), and the second frame period starts at time T28 (F_(f) is aframe frequency). The times T1 to T32 are shown in FIGS. 19 to 21 inorder to explain the operation performed with the time division method.In the initial state, all the backlight sections, #0 to #2, are turnedoff, and all the pixels or pels in the TFT LCD array 3 are reset, i.e.,cleared.

One of the R, G, and B LEDs for one backlight section is turned onfollowing the elapse of the response time T_(res) for the liquid crystalmaterial in the last pel line that the backlight section illuminate. Inthis example, the response time T_(res) is equal to the sum of twoperiods, i.e., the sum of two write cycles. The ON operation for eachbacklight section is continued for a predetermined period, e.g., a timeequivalent to the time allocated fro three write cycles. The R LED inthe backlight section #0, for example, is turned on at time T6 followingthe elapse of the response time T_(res) for the liquid crystal materialin the pel line I8, e.g., following the elapse of the times T4 and T5.The ON state of the backlight section #0 is continued from time T6 totime T8. Then, during the response time for the liquid crystal material,and the ON period for the backlight section, the next data, e.g., R dataR9 to R23, are written to the succeeding multiple pel lines.

The operation during a period extending from time T1 to time T8 is asfollows:

During a period extending from time T1 to T3, data R0 to R8 are writtenacross pel lines I0 to I8. The R LED for the backlight section #0 isturned on at time T6, following the elapse of the response time T_(res)for the liquid crystal material in the pel line I8. The ON state of theR LED for the backlight section #0 is continued from time T6 to time T8,and R data R0 to R8 are displayed. During the response time T_(res)i.e., a period extending from time T4 to T5, and during the ON periodfor the backlight section #0 is turned off before the next data G0 to G2are written across the pel line I0 to I2 at time T10. Time T9 is used asa margin between the ON period for the backlight section #0 and theperiod for writing the next data G0 to G2.

The operation during a period extending from time T9 to time T11 is asfollows.

It should be noted that data R9 through R23 are written in pel lines I9through I23 during the preceding period extending from T4 to T6, i.e.,the response time T_(res) for the liquid crystal material in pel lineI8, and during the ON period for the R LED of the backlight section #0.The R LED for the backlight section #1 is turned on at time T9,following the elapse of the response time T_(res) for the liquid crystalmaterial in the pel line I17. The ON state of the R LED for thebacklight section #1 is continued from time T9 to time T11, and R dataR9 to R17 are displayed. During the ON period for the backlight section#1, i.e., during a period extending from T9 to T11, the succeeding dataR24 to R26 are written across the succeeding pel lines I24 to I26, and Gdata G0 to G5 are written across pel lines I0 to I5. It should be notedthat the R LED for the backlight section #1 is turned off before thenext data G9 to G11 are written across the pel lines I9 to I11 at timeT13. Time T12 is used as a margin between the ON period for thebacklight section #1 and the period for writing the next data G9 to G11.

The operation during a period extending from time T12 to time T14 is asfollows.

It should be noted that data R18 through R26 are written in pel linesI18 through I26 during the preceding period extending from T7 to T9,i.e., the response time T_(res) for the liquid crystal material in pelline I17, and during the ON period for the R LED of the backlightsection #1. The R LED for the backlight section #2 is turned on at timeT12, following the elapse of the response time tres for the liquidcrystal material in the pel line I26 are displayed. During the ON periodfor the backlight section #2, the succeeding data G6 to G14 are writtenacross the succeeding pel lines I6 to I14. It should be noted that the RLED for the backlight section #2 is turned off before the next data G18and G20 are written across the pel lines I18 to I20 at time T16. TimeT15 is used as a margin between the ON period for the backlight section#2 and the period for writing the next data G18 to G20.

The operation during a period extending from time T15 to time T17 is asfollows.

It should be noted that data G0 through G8 are written across pel lineI0 through I8 during the preceding period extending from T10 to T12,i.e., the response time T_(res) for the liquid crystal material in pelline I26, and during the ON period for the R LED of the backlightsection #2. The G LED for the backlight section #0 is turned on at timeT15, following the elapse of the response time T_(res) for the liquidcrystal material in the pel line I8. The ON state of the G LED for thebacklight section #0 is continued from time T15 to time T17, and G dataG0 to G8 are displayed. During the ON period for the backlight section#0, the succeeding data G15 to G23 are written across the succeeding pellines I15 to I23. It should be noted that the G LED for the backlightsection #0 is turned off before the next data B0 to B2 are writtenacross the pel lines I0 to I2 at time T19. Time T18 is used as a marginbetween the ON period for the backlight section #0 and the period forwriting the next data B0 to B2.

In this manner, the G LED for the backlight section #1 is maintained onfor a period extending from time T18 to T20, and the G LED for thebacklight section #2 is maintained on for a period extending from timeT21 to T23.

The operation during a period extending from time T24 to time T26 is asfollows.

It should be noted that data B0 through B8 are written across pel linesI0 through I8 during the preceding period extending from T19 to T21. TheB LED for the backlight section #0 is turned on at time T24, followingthe elapse of the response time T_(res) for the liquid crystal materialin the pel line I8. The ON state of the B LED for the backlight section#0 is continued from time T24 to time T26, and B data B0 to B8 aredisplayed. During the ON period for the backlight section #0, thesucceeding data B15 to B23 are written across the succeeding data B15 toB23 are written across the succeeding pel lines I15 to I23. It should benoted that the B LED for the backlight section #0 is turned off beforethe next dat R0 to R2 are written across the pel lines I0 to I2 at timeT28. Time T27 is used as a margin between the ON period for thebacklight section #0 and the period for writing the next data R0 to R2.

The operation during a period extending from time T27 to time T29 is asfollows.

It should be noted that data B9 through B17 are written across pel linesI9 through I17 during the preceding period extending from T22 to T24.The B LED for the backlight section #1 is turned on at time T27,following the elapse of the response time T_(res) for the liquid crystalmaterial in the pel line I17. The ON state of the B LED for thebacklight section #1 is continued from time T27 to time T29, and B dataB9 to B17 are displayed. During the ON period for the backlight section#1, the succeeding data B24 to B26 are written across the succeeding pellines I24 to I26, and R data R0 to R5 are again written across pel linesI0 to I5. It should be noted that the B LED for the backlight section #1is turned off before the next data R9 to R11 are written across the pellines I9 to I11 at time T31. Time T30 is used as a margin between the ONperiod for the backlight section #1 and the period for writing the nextdata R9 to R11.

The operation during a period extending from time T30 to time T32 is asfollows.

It should be noted that dat B18 through B26 are written across pel linesI18 through I26 during the preceding period extending from T25 to T27.The B LED for the backlight section #2 is turned on at time T30,following the elapse of the response time T_(res) for the liquid crystalmaterial in the pel line 126. The ON state of the B LED for thebacklight section #2 is continued from time T30 to time T32, and B dataB18 to B26 are displayed. During the ON period for the backlight section#2, the succeeding data R6 to R14 are written across the succeeding pellines I6 to I14. It should be noted that the B LED for the backlightsection #2 is turned off before the next data R18 to R20 are writtenacross the pel lines I18 to I20 at time T34 (not shown). Time T33 (notshown) is used as a margin between the ON period for the backlightsection #2 and the period for writing the next data R18 to R20.

Table 4 shows the timings for the display of R, G and B color images onthe pel lines during the first from period, extending from time T1 toT27, and during the second frame period, extending from time T28 to T35.

TABLE 4 Period Backlight section Color T6-T8 B/L #0 R  T9-T11 B/L #1 R T-12 B/L #2 R T15-T17 B/L #0 G T18-T20 B/L #1 G T21-T23 B/L #2 GT24-T26 B/L #0 B T27-T29 B/L #1 B T30-T32 B/L #2 B

The above operation is repeated to display color images on the TFT LCDarray 3.

In FIGS. 22 and 23 are shown the statuses of an image displayed on theTFT LCD array at times T6 and T15. In FIG. 22, at time T6, while dataR15 to R17 are being written across pel lines I15 to I17, the R LED forthe backlight section #0 is turned on. Accordingly, R data on pel linesI0 to I8 are displayed, and the R data n the pel lines I9 to I17 are notdisplayed. In FIG. 23, at time T15, while data G15 to G17 are beingwritten to pel lines T15 to I17, the G LED for the backlight section #0is turned on. Accordingly, G data on pel lines I0 to I8 are displayed,and the data G9 through G17 and the dat R18 through R26 are notdisplayed.

In FIG. 24 is shown another example for the backlight 4. An LED array 20is mounted on a substrate 21, and lines #0 to #8 each include R, G and BLEDs 22. The backlight driver 8 selectively activates the R, G and BLEDs. Light emitted by the R, G and B LEDs are transmitted through alight scattering sheet 23 to the TFT LCD array 3.

The present invention has been explained while referring to the firstand the second embodiments for which Y=27, i.e., the TFT LCD array 3includes 27 pel lines. It is, however, apparent that the presentinvention can be applied for either the SGA, the SXGA, the UXGA or theQXGA scheme shown in Table 3.

According to the present invention, an LCD device is provided that canbe operated at a higher speed than can the conventional field sequentialscheme.

While the invention has been particularly shown and described withrespect to preferred embodiments thereof, it will be understood by thoseskilled in the art that the foregoing and other changes in form anddetails may be made therein without departing form the spirit and scopeof the invention.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent(s):
 1. A liquid crystal display devicecomprising: a liquid crystal display array divided into a first area, asecond area and a third area, in each of which are included a pluralityof pel lines; a first means for simultaneously performing an operationfor sequentially writing first color data, selected from data providedfor red, green and blue, along said plurality of pel lines in said firstarea, an operation for sequentially writing second color data, selectedfrom said data provided for red, green and blue, along said plurality ofpel lines in said second area, and an operation for sequentially writingthird color data, selected from said data provided for red, green andblue, along said plurality of pel lines in said third area; a backlightmeans, which is divided into N backlight sections, N being a multiple of3 and is equal to or greater than 6, and which selectively generates redlight, green light or blue light, wherewith N/3 backlight sectionsilluminate said first area, N/3 backlight sections illuminate saidsecond area and N/3 backlight sections illuminate said third area; and asecond means for sequentially activating said N/3 backlight sections forsaid first area to generate first color light and sequentiallydisplaying said first color data in said first area, for sequentiallyactivating said N/3 backlight sections for said second area to generatesecond color light and sequentially displaying said second color data insaid second area, and for sequentially activating said N/3 backlightsections for said third area to generate third color light andsequentially displaying said third color data in said third area,wherein the second means performs simultaneously the operation ofsequentially activating said N/3 backlight sections for each color ineach said first, second and third areas.
 2. The liquid crystal displaydevice according to claim 1, wherein said first means performssimultaneously said operation for writing said first color data, saidoperation for writing said second color data and said operation forwriting said third color data.
 3. The liquid crystal display deviceaccording to claim 2, wherein said first area, said second area and saidthird area are each divided into N/3 sub-areas, and in each of saidsub-areas are included a plurality of pel lines.
 4. The liquid crystaldisplay device according to claim 3, wherein, when one color data set iswritten in one of said sub-areas, said second means activates abacklight section assigned for said sub-area, and before another colordata set is written in said sub-area, said second means deactivates saidbacklight section.
 5. The liquid crystal display device according toclaim 2, wherein the same number of pel lines are included in said firstarea, said second area and said third area.
 6. The liquid crystaldisplay device according to claim 3, wherein, when one part of one colordata set is displayed in one of said sub-areas, the following part ofsaid color data is written in the succeeding sub-area.
 7. The liquidcrystal display device according to claim 3, wherein, when one part ofone color data set is displayed in one of said sub-area, the followingpart of said color data is written across said pel lines in thesucceeding multiple sub-areas.
 8. The liquid crystal display deviceaccording to claim 3, wherein a backlight section assigned for one ofsaid sub-areas is turned on following the expiration of a response timefor a liquid crystal material in the last pel line in said sub-area. 9.The liquid crystal display device according to claim 3, wherein saidfirst means writes said first color data, said second color data andsaid third color data at predetermined intervals in one of saidsub-areas, and a backlight section assigned for said sub-area generateslight for said first color when said first color data have been written,generates light for said second color when said second color data havebeen written, and generates light for said third color when said thirdcolor data have been written.
 10. The liquid crystal display deviceaccording to claim 3, wherein said second means controls said Nbacklight sections so as to sequentially display said color data writtenin said sub-areas during a period 1/F_(f) (F_(f) is a frame frequency).11. A liquid crystal display device comprising: a liquid crystal displayarray, which includes horizontally arranged X pels and verticallyarranged Y pels, which is divided into a first area, a second area and athird area, in each of which are included horizontally extended Y/3 pellines, and which is divided into N/3 sub-areas, N being a multiple of 3and is equal to or greater than 6; a first means for simultaneouslyperforming an operation for sequentially writing first color data,selected from data provided for red, green and blue, across Y pel linesbeginning with the first pel line in said first area, continuing throughsaid pel lines in said second area and ending with the last pel line insaid third area, for performing an operation for sequentially writingsecond color data, selected from said data provided for red, green andblue, across Y pel lines beginning with the first pel line in saidsecond area, continuing through said pel lines in said third area andending with the last pel line in said first area, and for performing anoperation for sequentially writing third color data selected from saidred, green and blue data into Y pel lines beginning with the first pelline in said third area, continuing through said pel lines in said firstarea and ending with the last pel line in said second area; a backlightmeans, which is divided into N backlight sections and which selectivelygenerates red light, green light or blue light, wherewith N/3 backlightsections illuminate said first area, N/3 backlight sections illuminatesaid second area and N/3 backlight sections illuminate said third area;and a second means for controlling said N backlight sections, so thatwhen one color data set, selected from said data provided for red, greenand blue, have been written to one of said sub-areas, a backlightsection assigned for said sub-area is turned on to generate a lighthaving the same color as said color data set, wherein said second meansperforms simultaneously said operation for sequentially activating saidN/3 backlight sections for each color in each said first, second andthird areas.
 12. The liquid crystal display device according to claim11, wherein, when one color data set is written in one of saidsub-areas, said second means activates a backlight section assigned forsaid sub-area, and before another color data set is written in saidsub-area, said second means deactivates said backlight section.
 13. Theliquid crystal display device according to claim 11, wherein, when onepart of one color data set is displayed in one of said sub-areas, thefollowing part of said color data is written in the succeeding sub-area.14. The liquid crystal display device according to claim 11, wherein,when one part of one color data set is displayed in one of saidsub-areas, the following part of said color data is written across saidpel lines in the succeeding multiple sub-area.
 15. The liquid crystaldisplay device according to claim 11, wherein a backlight sectionassigned for one of said sub-areas is turned on following the expirationof a response time for a liquid crystal material in the last pel line insaid sub-area.
 16. The liquid crystal display device according to claim11, wherein said first means writes said first color data, said secondcolor data and said third color data at predetermined intervals in oneof said sub-areas, and a backlight section assigned for said sub-areagenerates light for said first color when said first color data havebeen written generates light for said second color when said secondcolor data have been written, and generates light for said third colorwhen said third color data have been written.
 17. The liquid crystaldisplay device according to claim 11, wherein said second means controlssaid N backlight sections so as to sequentially display said color datawritten in said sub-areas during a period 1/F_(f) (F_(f) is a framefrequency).
 18. A liquid crystal display device comprising: a liquidcrystal display array, each of which includes plurality of pel linesthat are sorted into a plurality of pel line groups, each of whichincludes at least two continuous pel lines; a first means forsequentially writing to said plurality of pel line groups first colordata selected from data provided for red, green and blue, forsequentially writing to said plurality of pel line groups second colordata selected from said data provided for red, green and blue, and forsequentially writing to said plurality of pel line groups third colordata selected from said data provided for red, green and blue, each ofsaid pel lines in a pel lines group being driven simultaneously duringeach sequence; a backlight means, which is divided into N backlightsections (N is an integer equal to or greater than 2) and whichselectively generates red light, green light or blue light, whereof eachof said N backlight sections is assigned for a 1/N area in said liquidcrystal display array; and a second means for sequentially activatingsaid N backlight sections in order to sequentially display said colordata written across said plurality of pel line groups in said liquidcrystal display array.
 19. The liquid crystal display device accordingto claim 18, wherein, when one color data set has been written acrosspel lines in said 1/N area, said second means activates a backlightsection assigned for said 1/N area to generate a light having the samecolor as said color data set, and then, before another color data set iswritten to said 1/N area, said second means deactivates said backlightsection.
 20. The liquid crystal display device according to claim 18,wherein, when one part of one color data set is displayed in one 1/Narea, the following part of said color data is written in the succeeding1/N area.
 21. The liquid crystal display device according to claim 18,wherein, when one part of one color data set is displayed in one 1/Narea, the following part of said color data is written across said pellines in the succeeding multiple 1/N areas.
 22. The liquid crystaldisplay device according to claim 18, wherein a backlight sectionassigned for one 1/N area is turned on following the expiration ofresponse time for a liquid crystal material in the last pel line in said1/N area.